Back when I was into Corvairs, some of which had a very primitive turbo setup, exhaust wrapping (essentially insulating the exhaust prior to the turbo to maximize pressures) was a common mod and provided an effective performance gain (especially on the lower end) with no real downside. This car was odd, had a long pipe from the exhaust manifolds to the turbo (car was an aircooled flat 6 like a Porsche, pipes ran from under the engine up into the engine compartment where the turbo sat above the engine, this is the part which was wrapped). The position of the EVO turbo obviously means it's less prone to the pressure losses this wrapping helped eliminate, but still I'm wondering if some form of this technique, (maybe insulating the exhaust manifold somehow?) would be of use on our cars?

Dan

 

If nothing else, it keeps the engine bay cooler.

 

I was thinking no one would reply to this, really seems like an potential area of easily installed/trouble free/CHEAP improvement to me. And you're right, lowered underhood temps are a bonus, which can also boost performance a tad.

I see on your web page you offer lower ratio accessory drive pulleys for the WRX. This was another speed trick on the Corvair, since the belt driven air-cooling fan took a lot of hp, especially at high rpm. For drag racing they'd often disconnect the belt for the run, then re-connect at the end of the 1/4 mile. You could get a variable ratio pulley to allow you to select the amount of reduction.

Dan

 

I think you can also gain some gas velocity by wrapping the downpipe because it keeps the temps up. I have seen a few Turbo insulation kits that actully insulate the exhaust side of the turbo with a metalic insulating blanket. Without going to an aftermarket manifold I'm not sure you could effectivly wrap the stock manifold, but then again I have not pulled off the heatshield yet to look.

I think it is worth trying if nothing else it would cut down the underhood temps. Go for a turbo wrap kit and some header wrap for the manifold and downpipe.

 

...I'd pay for a good ceramic coating first... Al liked it on his header from Quantum...

 

I was into Turbo Corvairs and I can tell you that the heavy wrap of the system going into the turbo created results that you could really feel. I used to drag race these things and the results were dramatic. I used to be told (years) that turbos work on the heat not just the exhaust force and this was why it helped so much. Seems like a better application for a WRX/STI with uppipes would help more than than an Evo. But once we go with headers on the Evo we will need to do something to reduce underhood temperature so we will get a double benifit from header coating and wrap. Based on my positive experiences many years ago, I would go for this mod. when I install a header.

 

I've seen a considerable difference on OE Mitsubishi headers... Swain Tech on the VR4's and I forget which was used on the GSX/T's... granted, we're talking about bigger turbo's on the OE manifolds, but it worked well... VERY noticeable reduction of under hood temps and a noticeable decrease in spool time. Of course, a well-designed tubular header is optimum. However, don't dismiss the advantages of coating an OE piece.

 

ps I'm not knocking wrapping for race purposes... but for the street, the wrap will hold water, and has a history of accelerating oxidation... probably not good on the open hood of the Evo...

 

Sounds a LOT like another strange car - the SLOWbaru!

 

I was wondering how can the Header Wraps hold the water if they repel most of the water if they are wraped correctly. Also won't the headers rust slower or less with the wrap on?
One more thing, when bring the car to the dealer for service will it void any warranties with the header wraps? Just wana know since I am new at this.

Thanx

 

I remember about the only rub with the Corvair wrap was that it did accelerate rusting of the pipes, in this car though much of the wrapped area is well under the car & subject to more splash than would be the case on the EVO. Also people would insulate the entire exhaust side of the turbo itself, to some additional advantage.

Dan

 

...did they have a big hole cut in the hood over the header, with an inch+ gap between the head and heat shield?

 

Ever pull a factory heat shield off an exhuast or down pipe?

What is in there?


Its fiberglass insulation. Most of the areas where wrap is most effective get very very hot. Any mosture won't last long.

Id wrap the exhuast manifold really well and put the heat sheild over it.


Then Id wrap the downpipe and wrap again in either the insulation backed aluminum foil (foil out) or make thin metal heatshields on the order of the OE ones but to fit the new pipe.

Those ceramic coatings are good looking but expensive. You can also easily beat the R factor of that stuff by a long shot with real insulation and those heat sheilds.